Rumors claim that AMD shipped RDNA 3 Navi 31 A0 GPU Silicon in the Radeon RX 7900 series

AMD recently launched its flagship RDNA 3 offering based on its Navi 31 GPUs, the Radeon RX 7900 series. While I pitted the AMD Navi 31 against NVIDIA’s RTX 4080, the final performance was a bit underwhelming and wasn’t the massive upset everyone expected. Rumors now suggest that the reason behind such lackluster performance could be due to the incomplete GPU silicon shipped on the main cards.

AMD Allegedly Shipped RDNA 3 ‘Navi 31’ GPU Silicon With Radeon RX 7900 Series Graphics Cards

As he discovered it Kepler 2It appears that early RDNA 3 silicone had a non-working pre-HW shader. This appeared in three chipsets, the GFX1100 (Navi 31), GFX1102 (Navi 33), and GFX1103 (an APU lineup consisting of Phoenix chipsets). It is now based on the latest GitHub submission. Kepler also suggests that Navi 32 GPUs are physically based on IP “GFX1103” while Navi 33 chipsets feature IP “GFX1102”. The same issues are found on every other chip besides Navi 32 which will be featured in many mainstream discrete GPUs on desktop and mobile platforms by early 2023.

According to Kepler, this is something that can’t be fixed or revised in a few weeks and will take several months if AMD plans to fix this. It would be a huge blow if the newer silicon showed up with the fix a few months later because the majority of gamers had already purchased the early revision of the Radeon RX 7900 series with the unfinished silicon. AMD will likely prepare an update a year later that will address these issues, but for now, the Radeon RX 7900 series may have to rely heavily on driver-level improvements to address the patchy GPU nature of their RDNA 3 silicon.

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But that’s not all, other key features like VOPD instructions featured in RDNA 3 GPUs claimed to offer a significant performance improvement but in reality, they only managed to deliver a 4 percent improvement over RDNA 2 in ray tracing titles. The RDNA 3 silicon is designed to handle dual Wave32 instructions to double the floating point performance through the use of 64 multi-precision multi-purpose ALUs implemented across two SIMD32 modules. Speaking to an AMD representative, the folks over at HardwareTimes were able to confirm that AMD is currently working on performance tuning here and expect improvements along the way:

Wave64 can access new ALUs for 2x execution rates to unlock performance during heavy ALU code execution. For Wave32 mode, the compiler rearranges and packages the instructions into VOPD encoding. Our RT test scene using VOPD encodings provided an approximately 4% increase in frames per second by removing the ALU bottleneck. We expect to see more improvements as the compiler matures with more improvements for mapping code sequences to VOPD encodings. And with advances in using AI-based, root-based, and computing-based rendering technologies for more photorealistic rendering, we expect to see ALU-related symbols that will take advantage of these new ALUs more and more.

AMD rep via HardwareTimes

Reviewers who also got a first look at several AMD Radeon RX 7900 series dedicated graphics cards also reported inconsistent and choppy clock speeds on the cards.

Here is a breakdown of all AMD GPU architectures released since Vega:

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Graphics engineering GPU CODENAME alternative name Architectural Engineering Producer
GFX900 Vega 10 GCN 5.0 RX VEGA / Radeon Pro
GFX902 black Crow Raven Ridge / Picasso GCN 5.0 Ryzen 2000/3000 (G/GE)
GFX904 Vega 12 GCN 5.0 Vega Pro 20 (Mac)
GFX906 Vega 20 GCN 5.0 Radeon VII / Radeon Pro VII
GFX908 Arcturus CDNA 1 MI100 instinct
GFX90A Aldebaran CDNA 2 MI200 Instinct
GFX909 Crow 2 GCN 5.0 TBC
GFX909 Renoir GCN 5.0 Ryzen 4000 (H/U/G)
GFX1010 Navi 10 RNA 1 RX 5700/5600 (M/XT)
GFX1011 Navi 12 RNA 1 PRO 5600M (MAC)
GFX1012 Navi 14 RNA 1 RX 5500 (M/XT)
(GFX 1030) Navi 21 Big Navy / Sienna Cichlids RNA 2 RX 6900/6800 series
(GFX1031) Navi 22 marine flounder RNA 2 RX 6700 series
GFX1032 Navi 23 Demagry Cavfish RNA 2 RX 6600 series
(GFX 1033) Navi 24 Goby beige RNA 2 RX 6500/6400 series
(GFX 1033) Van Gogh Aerith RNA 2 steam surface
(GFX 1036) Raphael RNA 2 Ryzen 7000?
GFX1040 Van Gogh Light / Mendocino green sardines RNA 2 Ryzen 7000?
GFX1100 Navi 31 Plum bonito RNA 3 Radeon RX 7900
GFX1101 Navi 32 Wheat is people RNA 3 Radeon RX 7800
GFX1102 Navi 33 Hotpink bonefish RNA 3 Radeon RX 7700?
GFX1103 Navi 3X Phoenix Point RNA 3 Ryzen 7000 APU?
(GFX 1200) Navi 4x RNA 4 Radeon RX 8000?

The days ahead for RDNA 3 and especially the Radeon RX 7900 graphics cards based on the Navi 31 GPU silicon will be interesting. Extreme overclockers have told us that they can’t install their cards at higher clock speeds since silicon is severely restricted by power limits and it makes absolutely no sense to do LN2 OC with existing BIOS.

What do you think of the launch of AMD’s Radeon RX 7900 series?

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